1. Field of this Invention
This invention relates to graft copolymers derived from trunk copolymers of ethylene and .alpha.,.beta.-ethylenically unsaturated monocarboxylic acids and from grafted branches of polyamide.
2. Description of the Prior Art
Graft copolymers of modified polyolefins and polyamides are well known. Polyamides have been polymerized from monomer in the presence of trunk copolymers. U.S. Pat. No. 3,388,186 discloses formation of a graft copolymer by polymerizing polyamide monomer in a melt of copolymer backbone having active sites for grafting. U.S. Pat. No. 3,465,059 and U.S. Pat. No. 3,634,543 also disclose preparation of graft copolymers by a process of polymerization in the presence of completely-formed backbone copolymer.
Grafting reactions have been disclosed between a polyamide as side chains and certain copolymers of olefin and .alpha.,.beta.-ethylenically unsaturated carboxylic acid as the trunk copolymer. U.S. Pat. No. 4,017,557 discloses such grafting reactions wherein the trunk copolymer contains vicinal reaction sites for grafting attachment of the side chains. U.S. Pat. No. 3,976,720 and U.S. Pat. No. 3,972,961 also disclose grafting reactions which require vicinal acid pairs or acid-ester groups.
U.S. Pat. No. 3,963,799 discloses a blend of polyethylene and polyamide with a graft copolymer of polyamide grafted to vicinal reaction sites in a trunk copolymer of olefin and .alpha.,.beta.-ethylenically unsaturated carboxylic acid. The graft copolymer is said to reduce interfacial free energy of the blend.
Another blend of polymers is disclosed in U.S. Pat. No. 3,676,400 wherein polyamide and unneutralized copolymers of olefin and .alpha.,.beta.-ethylenically unsaturated monocarboxylic acid are milled together. The patent contains no suggestion of graft polymerization.
Neutralization of copolymers including olefins and .alpha.,.beta.-ethylenically unsaturated carboxylic acids is well known. U.S. Pat. No. 3,264,272 discloses such neutralization using a variety of metals and disclosing alkali metals as preferred. U.S. Pat. No. 3,437,718 discloses the use of such neutralized copolymers to compatibilize two other copolymers in a blend. There is no mention of graft polymerization.
U.S. Pat. No. 4,078,014 issued Mar. 7, 1978 on an application filed, June 10, 1976, in the names of the inventors herein, discloses a blend of polyethylene and polyamide with a copolymer of ethylene and neutralized .alpha.,.beta.-ethylenically unsaturated carboxylic acid to serve as a compatibilizing material. It is stated in the body of that patent, that some graft copolymer may be formed by blending the polyamide with the neutralized ethylene-carboxylic acid copolymer.